Abstract

RODRIGUEZ-PEREZ, J. Enrique et al. Genetic erosion of the three-way line maize hybrid parents of a synthetic variety. Agrociencia [online]. 2016, vol.50, n.8, pp.1081-1090. ISSN 2521-9766.

The advanced generations of three-way line maize (Zea maize L.) hybrids (THs) could be considered synthetic varieties (SVs) formed by random mating of their lines (Sin L). However, it was shown that there are differences depending on the type of hybrid and the inbreeding coefficient of the lines that form the hybrids (F), among other factors. To investigate the THs in this context, the loss of genes that are non-identical by descent (NIBD) was determined, which takes place during the formation of the sample of the m individuals that represent each one as parent of an SV. The hypothesis of the study was that genetic erosion does occur. The use of non-related lines was considered and that each one comprises a virtual population with 2-F NIBD genes. The average number of NIBD genes lost by a TH per sampling (GNIBDP) is expressed as 3(2-F) minus the number of NIBD genes that reach the sample. It was found that GNIBDP is inversely related with m and F. If F=1, in order for GNIBDP to be 0.15 or less, m must be equal to or greater than 4, or 15 or more when F=0. These numbers indicate that erosion should not occur with samples of several hundred, as occurs in seed production. When F>0 the imbalance of the gene frequencies of the lines in each TH should produce an inbreeding coefficient in the Sin t higher than that of Sin L.

Keywords : Genes; non-identical by descent; inbreeding coefficient; Zea mays L.

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